Copolyesters containing 1,4-cyclohexanedimethanol (CHDM) are useful materials for injection molding and extrusion. For many applications these polymers have sufficient toughness but there is a need for further improvements in toughness, especially at low temperatures.
The use of epoxy modified polymers in blends with polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) is known. An ethylene/ethylacrylate/glycidylmethacrylate copolymer blended with PBT was reported by M. Hert, J. C. Jannet and P. Robert (Sixth Annual Meeting of the Polymer Processing Society, Apr. 7-20, 1990). There are no known references Which disclose the specific, unexpected effectiveness of epoxy modified polyolefins in CHDM-containing copolyesters, however.
This invention relates to a class of polyolefin compounds containing reactive epoxy groups which are unexpectedly efficient in increasing the low temperature impact strength of CHDM containing copolyesters.